Means for controlling electric current.



V. M. HARRIS.

MEANS FOR CONTROLLING ELECTRiC CURRENT.

APPLICATION men oer; 12, me.

1,268,348. Patented June 4,1918.

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V. M. HARRIS.

' MEANS FOR CONTROLLING ELECTRIC CURRENT.

APPLICATION FILED OCT. I2, 1916.

1 ,26 8 ,348. Patented June 4, 1918,

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V. M. HARRIS.

MEANS FOR CONTROLLING ELECTRIC CURRENT.

APPLICATION FILED OCT. 12. 1916.

Patented June 4, 19l8.

3 SHEETS-SHEET 3- VABIAN M. HARRIS, OF CHICAGO, ILLINOIS.

MEANS FOR CONTROLLING ELECTRIC CURRENT.

Specification of Letter: Patent.

Patented June 4, 1918.

Application filed October 12, 1916. Serial No. 125,295.

To all whom it may concern:

Be it known that I, VARIAN M. HARRIS, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Means for Controlling Electric Current, of which the following is a s ecification.

ne of the objects of my invention is to provide improved means for controlling an electric current, when used for an electrothermic device and regulating the temperature of such devices, or maintaining it substantially constant by intermittently closing and opening the electric circuit containing such device upon given variation of temperature thereof, above and below a predetermined normal degree that may be established by adjusting the heat responsive member.

Another object of my invention is generally to improve mechanisms of this character.

Other, further and more specific objects of my invention will become readily apparent to persons skilled in the art, from a consideration of the following description when taken in conjunction with the drawings, wherein Figure 1 is an elevation of an electI'o-thermic device, embodied in a flat iron and my current controlling and heat regulating mechanism.

Fi 2 is a side elevation of the automatic switc for controlling the heating current.

Fig. 3 is a section taken on line 33 of Fig. 4 is an end view of the switch mechanism.

Fig. 5 is an attaching plug for the fiat iron circult.

Fig. 6 is a section taken on line 6-6 of Fi 3. I Fig. 7 is a schematic arrangement of partsr Fig. 8 is a simplified diagram of circuits.

In all the views the same reference'charactors are employed to indicate similar parts.

10 is a fiat iron of usual form, adapted to be heated by an electric current,the heatin sections of which are not shown,provi ed with the usual terminals 11 and 12. The handle 13, preferably of some heat insulating material, is secured to the flat iron body by depending arms 14 and 15. 16 is the usual connecting plug for containing the contacts in cooperation with the terminals l1 and 12. Such a structure is usual in flat irons adapted to be heated by an electric current.

My attaching means, for controlling the current and for regulating the heat, con sists of a double-pole switch structure 17, adapted to be supported in a proper electrical receptacle by the attaching plug 18,

,. energized by current of this character.

The magnet is provided with a core 21, which is preferably laminated, secured at its inactive end to a return yoke 22, which terminates at the front active end of the magnet, substantially in the same transverse plane with the core 21. The coil 20 is provided with insulating heads 23, 24, secured to the respective ends of the core 21, wound with wire 25 to produce the proper number of ampere turns, and of suitable resistance for this purpose. The electro-magnet is mounted upon a frame 26, secured at its rear, end to a plate of insulating material 27, which in turn is fixed to the attaching plug 18 for insertion in a receptacle of an electric circuit communicatin with a source of electric current supply. he magnet also carries an insulating plate 27 which supports the switch 28.

tanding outwardly from the switch 27 are. two pairs of terminal switch posts 29, 29 and 30, 30. Secured to these terminals are resilient fingers or switch blades 31, 31 and 32, 32, respectively.

A plate 33 is secured on the end of the spool head 23 and is provided with outwardly extending arms 3434 between which is hinged an armature 35, as at 36. Secured to the armature 35 is a rearwardly extending arm 37. Carried on the rear end of the arm 37 are two spaced apart insulated washers 38, for cooperation with switch blades 31 and 32' for closing the circuit between them, when the coil 20 is energized and the armature 35 is attracted by the electro-magnet. Other spaced-apart washers 39 are also insulated and carried by the arm 37 and are adaptedior closing the circuit between the resilient fingers 31 and 32 of the switch when the armature is attracted by'the electro-magnct. The armature 35 is slotted to provide two parallel legs 35. and 35*. Another armature 38 is pivoted at the free ends of the armature 35, as at 39, and carries an outwardly projecting latch member 40. A sp'rlng 41 is connected to the armature 48, and to an ad ustable screw 42, which passes through the end 26, of the frame member 26, and is held in place by the adjusting nuts 4343. A stop 44 is secured on the armature 35 and limits the outward movement of the armature, 38. A bracket 45 is secured to the frame member 26, the end of which engages the end of the latch member 40 of the armature 38, when the compound armature is attracted by the electro-magnet.

When the armature 35 is attracted by the electro-magnet 20, the bracket 45' will hold the armatures in 'substantiall 'the relative positions shown in Fig. 1, unti the outer end of the latch 40 passes the end of the bracket 41 whereupon the armature 38 will move more closely to the ele'ctro-magnet core, causing the end of the latch to engage the end of .the bracket thereby mechanically looking or holding the compound armature in its attracted position toward the magnet. This operation wedges the armature into close contact with the core and prevents rattling due to the current vibrations set up by the alternating current. disengagement of the armature when impact or jar is sufficient to overcome the magnetic portative eflect of the electro-magnet. When the spring41 holds the armature in its retracted position, the circuit closing washers 38 and 39, as a result of this positlon of the armature, lie relatively close to the side of the electro-magnet. When the armature is attracted these washers, with the arm 37, are projected outwardly'until thewashers make electrical contact with the respective resilient switch fin ers 31, 31 and 32, 32 which closes the main eating circuit. p

The wires 50 and 51 are connected to the terminals 30 and 30 and the wires 52 and 53 are connected to the terminals 29, 29' and to the terminals 11 and 12 of the flat iron b the flexible cords or conductors 52 and 5%. The heat responsive device 19 consists of a relatively straight bar 54 and a relatively curved bar 55, fastened together at their ends 56 and 57; the end 56 being secured to a relatively stationary part, such as a clamp 58, the element being insulated therefrom and held in place by the screw 59. A similar clamp 60 isadjustably secured to the handle 15 of the flat iron by the screw 61 and carries a contact plate 62 insulated therefrom and secured in place by the screw 63. Thecontact plate carries an internally.

It also prevents threaded sleeve 64 provided with an index 65. An adjustable screw 66, provided wlth a thumb nut 67 on its outer end for convenient turning of the screw, also. carries a dial plate 68 for cooperation with the fixed mdex 65 to indicate the extent to which the screw has been turned.

The heat responsive element 19 is also provided with a contact 69 on its outer end for coiiperation with a contact 7 0 carried by the screw 66, I prefer that the bar 54 of the element 19 should have a much higher heatexpansion coefficient than the bar 55, so that a given intensity of heat, emanating from the iron 10, will expand the bar 54, or elongate it to a greater extent than the elongation produced in the bar 55, thereby causing connection between the contacts 69 and 7 O to be automatically broken. I also prefer that the current density of the bar 54 be greater than the-current density of the bar 55. This is an effect produced by the relation of the relative cross sections of the bars and their relative resistances. The object of such construction being that, after a definite periodmaintained may be controlled, to a large extent, by the rotation of the thumb nut 67 to advance or retract the screw 66 from the contact 69 of the expansion bar, requiring a greater or less change of temperature to open the circuit between the automatically moving bar and its relatively stationary contact and at'a higher or lower degree as the case may be.

For convenient placing of the thermostatic device on the flat iron, such as the handle arms 14 and 15 I provide the clamps 58 and 60 and theclamp screws 58 and 60' respectively. and on the rear clamp 58 I secure a plate 71 bearing an insulating plate 72 and two projecting terminals 73 and 74, and I secure on the insulating plug 16 corresponding spring terminals 75 and 76 for cob eration with the relatively fixed termina s 73 and 74 when the plug 16 is put in lace on the usual terminals 11 and 12 of the at iron. I connect the contact plate 62 with the terminal 73 by the wire 78 and I connect the fixed end 56 of the thermostatic element with the terminal 74 by the wire 79. The wires 80 and 81 are connected respectively to the terminals 30 and to the electro-ma et winding 25, as more clearl shown in Fig. 7. The

other terminal 83 o the ,electro-magnet is The use and operation of the apparatus will be apparent to persons skilled in the art from the foregoing description when taken in conjunction with the drawings, and while I have herein illustrated a single embodiment of my invention for the purpose of clear disclosure it will be manifest that many changes may be made in the general form or configuration and disposition of the parts, within the scope of the appended claims.

Having described my invention, what I claim is 1. In combination with an electro-thermic device arranged to be heated by an electric current; a double-pole switch in circuit with said device; an electro-magnet for operating said switch; a heat-responsive switch, within the influence of the thermic device,

.for denergizing said electro-magnet upon an abnormal increase of temperature of said thermic device and an attaching plug for supporting said magnet and double-pole switch when inserted in a plug receptacle.

2. In combination with an electro-thermic device arranged to be heated by an electric current; a double-pole switchin circuit with said device; an electro-magnet for operating said switch; a signal lamp in circuit with said electro-magnet; a heat-responsive switch located above but within the heat influence of said thermic device, for dee'nergizing said magnet upon abnormal increase'of temperature of said thermic device, and an attaching plug for supporting said magnet, signal lamp and double-pole switch when inserted in a suitable receptacle.

3. In combination with an electro-thermic device having a pair of projecting terminals; a plug having terminals whereby to connect said device with a source of current-supply by engagement with said terminals of the thermic device; a heat-responsive device detachably secured to said thermic device, having a pair of similar terminals and a pair of springl pressed terminals on said plug to engage t e terminals of said responsive device.

4. In combination with an electro-thermic device, to be heated by electric current, and

having a pair of projecting terminals; a.

plug having terminals whereby to connect said device with a source of current-supply by engagement with the terminals of the thermic device; a heat-responsive device secured to said thermic device, having a pair of similar terminals; a pair of springpressed terminals on said plug to engage the terminals of said responsive device; an automatic switch adapted and arranged in the heating circuit to be automatically closed when said thermic device is connected to said source of current-supply, and a closed circuit connecting said heat-responsive device and said switch to open the latter when the heat of said thermic device is increased beyond a predetermined degree.

In testimony whereof I hereunto set my I hand in the presence of two subscribing witnesses.

VARIAN M. HARRIS.

In the presence of Fomin BAIN, MARY F. ALLEN. 

